In general, in fields of information security, a method using mutually shared secret information and an encryptor is adopted as means for certifying one's own authenticity.
For example, in an IC card (Smart Card), etc., which are used for electronic settlement, an ID and secret information for individualizing the IC card are stored in an IC in the card. Further, the IC card has a cipher processing function for executing authentication based on the ID and secret information.
In another example, an authentication method called Content Protection for Recordable Media (CPRM) is specified as means for certifying authenticity of an SD (registered trademark) card in protection of copyrighted content.